You mean I have to clean them? Well yes you actually do. Gray water tanks accumulate soap scum on the sides of the tanks because most of the time people leave the valve open when camping so the tank mearly has water pass through it. Old soap scum along with food particles eventually will combine to make some nasty odors. If you have been camping for any length of time you will hear many different ways to freshen the gray water tank and in turn improve the accuracy of your holding tank gauge.
Before your next camping trip go to a pool supply store and buy a 32 ounce bottle of de-foamer solution. This is used in spa’s to eliminate the foam caused by detergent residue in peoples swimming suits. Stop and pick up 2 lbs of baking soda. Now after your next camping trip and before you head home fill the gray water tank about a third of the way. Add 6 ounces of the de-foaming agent down the kitchen sink and let the faucet run for a few minutes. Okay now drive home. The sloshing of the tank will neutralize soap scum and wash the tank walls clean. Leave this solution in the tank until you head out for your next camping trip or next campground. Before you head out add the 2 lbs of baking soda through the kitchen sink running water again for a few minutes. When you get to the campground dump the tank and you have cleaned out the gray water tank. Black water tanks are cleaned a little differently but moving the camper sloshing the mix around helps it get cleaned out also. So you could do both on the same trip. First, one of the biggest mistakes campers make is keeping the black water valve open when camping.
This is a no no as that allows the liquid to leave the tank and solids to build up. I have seen tanks so plugged we had to use a pressure washer to open them up. In the good old days all there was was a very strong smelling blue liquid that had formaldehyde in it. It did a very good job on odors but was very hard on campground septic systems. Today you have dozens of choices and the most environmentally correct are the enzymatic additives available from any camping supply store. These do a great job breaking down solids and actually help septic systems but don’t do as good a job of controlling odors like a formaldehyde based tank additive. You should wait till the tank is at least 1/2 full before dumping to allow these chemicals to act and liquefy wastes. If you have been camping and keeping the black tank valve open you can still clean the tank. Either way starting with an empty tank fill balck water tank about 1/3 of the way and add the recommended amount of black water tank additive. Some people have said adding a bag of ice will help but I find the tank gets clean enough from the constant sloshing of the water/additive mix. Drive home or to the next campground and at the next available hookup dump the tank. This should be enough to clean the tank and restore accuracy to the black water tank gauge. Now for the black water tank smells that will be next week…..